Islanded ac microgrid cluster hierarchical coordination control method and system

Abstract

This invention provides a hierarchical coordinated control method and system for islanded AC microgrid groups. The method includes: dividing the microgrid group into an upper-layer network based on microgrids and a lower-layer network based on distributed generation (DG) units; acquiring the state of each DG unit and constructing a droop control model for the lower-layer network and an upper-layer network based on a consensus protocol; performing coordinated control of the microgrid based on the lower-layer and upper-layer network droop control models; constructing a hierarchical power coordination control model for the microgrid group based on the coordination control results; and realizing hierarchical coordinated control of the microgrid group based on this model. This method, in addition to achieving consensus regulation, also realizes coordinated power control of the hierarchical structure of the microgrid group, effectively managing power sharing within the microgrid and power scheduling between microgrids, effectively supporting power regulation between different zones during network recovery.

Description

Technical Field

[0001] This invention relates to the field of microgrid control technology, and in particular to a hierarchical coordinated control method and system for islanded AC microgrid groups. Background Technology

[0002] Microgrid technology, as an important application of distributed power generation, has been widely adopted due to its flexibility, convenience, and intelligence, effectively resolving various contradictions faced by distributed power sources directly connected to the power system. However, microgrids have limited power supply capacity and are relatively vulnerable, potentially experiencing sudden power surges and large-scale load changes during operation. Connecting geographically proximate microgrids to form a microgrid cluster allows for power sharing within the cluster through coordinated control, improving the overall reliability and robustness of the system.

[0003] With the development of microgrid technology, microgrid cluster technology can significantly enhance the stability of microgrid operation and will become an important component of smart grids, addressing the challenges of large-scale, high-density, and intermittent distributed power sources in microgrids. However, compared to a single microgrid, the topology of a microgrid cluster, composed of multiple microgrids, is more complex, posing challenges to the coordinated control of the microgrid cluster system. Existing technologies lack effective scheduling methods for power sharing within the microgrid cluster system and power dispatch control between microgrids, especially during post-disaster islanding interconnection and power mutual assistance processes, failing to support power regulation between different zones during the network recovery phase. Summary of the Invention

[0004] This invention aims to provide a hierarchical coordinated control method and system for isolated AC microgrid groups to solve the above-mentioned technical problems. By performing hierarchical coordinated control on the microgrid group, it can effectively schedule and control the power sharing within the microgrid and the power between microgrids, effectively supporting power regulation between different zones during the network recovery phase.

[0005] To address the aforementioned technical problems, this invention provides a hierarchical coordinated control method for isolated AC microgrid groups, comprising the following steps:

[0006] Obtain the topology parameters of each microgrid and distributed power source in the isolated AC microgrid group, as well as the rated voltage parameters of the microgrid group;

[0007] Based on the topology parameters of microgrids and distributed generation, microgrid groups are divided into upper-layer networks with microgrids as the basic unit and lower-layer networks with distributed generation as the basic unit.

[0008] The rated voltage parameters of the lower network are determined based on the rated voltage parameters of the microgrid group, and a distributed power source is randomly selected from the lower network as the group head distributed power source according to the rated voltage parameters of the lower network.

[0009] Obtain the status of each distributed power source and construct a lower-level network vertical control model based on a consensus protocol;

[0010] Obtain the state of the distributed power source at the group head and construct an upper-layer network vertical control model based on the consensus protocol;

[0011] Coordinated control of microgrids is achieved based on lower-level network droop control models and upper-level network droop control models.

[0012] Based on the coordinated control results, a hierarchical power coordinated control model for microgrid groups is constructed, and hierarchical coordinated control of microgrid groups is realized based on the hierarchical power coordinated control model for microgrid groups.

[0013] The above scheme is based on the basic topology parameters of isolated AC microgrid groups and distributed generation, and fully considers the structure of the microgrid and the connections between microgrids. It establishes an upper-layer network with microgrids as the basic unit and a lower-layer network with distributed generation as the basic unit. Based on the consensus protocol, the lower-layer network droop control model and the upper-layer network droop control model can realize the consistent regulation of the system's frequency and voltage during the control process. On the basis of realizing the consistent regulation, a hierarchical power coordination control model of the microgrid group is also constructed, realizing the coordinated control of the hierarchical power of the microgrid group. It can effectively schedule and control the power sharing within the microgrid and the power between microgrids, and effectively support the power regulation between different zones during the network recovery phase.

[0014] Furthermore, the step of obtaining the state of each distributed power source and constructing a lower-layer network droop control model based on a consensus protocol specifically involves:

[0015] The status of each distributed power source is obtained based on the communication network between distributed power sources;

[0016] Based on the consensus protocol and the states of each distributed power source, a lower-layer network droop control model is constructed; the lower-layer network droop control model is expressed as follows:

[0017]

[0018] In the formula: τ represents the time constant of the response speed of the lower-layer network; This represents the angular frequency of the i-th distributed power source in the k-th microgrid after control. N represents the voltage after control of the i-th distributed generation in the k-th microgrid; j represents the j-th distributed generation; N k，i Represents the neighborhood set of a distributed power source; Let represent the positive vector of the i-th distributed source in the k-th microgrid; The adjacency matrix element represents the existence of a connection between the i-th and j-th distributed power sources; 0 indicates no connection, 1 indicates a connection. ω represents the angular frequency of the distributed power source before control. k，ch This represents the angular frequency of the distributed generation source at the head of the k-th microgrid group; This indicates whether a connection exists between the i-th distributed power source and the head distributed power source; 0 indicates no connection, 1 indicates a connection. k，ch This represents the voltage of the distributed power source at the head of the k-th microgrid group.

[0019] Furthermore, the step of obtaining the state of the distributed power source at the group head and constructing an upper-layer network droop control model based on a consensus protocol specifically involves:

[0020] The status of the group leader distributed power source is obtained based on the communication network between distributed power sources.

[0021] Based on the consensus protocol and the state of the distributed power source at the group head, an upper-layer network droop control model is constructed; the upper-layer network droop control model is expressed as follows:

[0022]

[0023] In the formula: T represents the time constant of the upper-layer network response speed; Represents the angular frequency of the distributed generation at the head of the k-th microgrid after control. represents the voltage after the distributed generation at the group head in the k-th microgrid is controlled; l represents the l-th microgrid; This represents the neighborhood of the k-th microgrid; This represents the positive vector of the k-th microgrid; This indicates whether a connection exists between the k-th microgrid and the l-th distributed power source; 0 indicates no connection and 1 indicates a connection exists. This indicates whether a connection exists between the k-th microgrid and the reference microgrid; 0 indicates no connection, and 1 indicates a connection. rated Indicates the reference angular frequency; v rated This represents the reference voltage.

[0024] In the above scheme, a consistency protocol is added to the traditional droop control, which can ensure the consistent regulation of the system's frequency and voltage during the control process.

[0025] Furthermore, a hierarchical power coordination control model for the microgrid group is constructed based on the coordination control results, and hierarchical coordination control of the microgrid group is realized based on the hierarchical power coordination control model, specifically as follows:

[0026] Based on the coordinated control results, the state of each distributed power source and the increase in the power generation cost of the head distributed power source are calculated using the power generation cost function.

[0027] Based on the principle of minimum power generation cost with constant increments, an optimal active power reduction model is constructed; the optimal active power reduction model is expressed as:

[0028] Δω cost =k ed λ ki (P ki )

[0029] In the formula: ω cost This represents the angular frequency of the distributed power source after cost optimization; k ed λ represents the positive scalar coefficient. ki (P ki ) represents the incremental value function of power generation cost; Δω cost Indicates the rate of slight increase in power generation costs;

[0030] Based on the increase in power generation costs and the optimal active power reduction model, a hierarchical power coordination control model for microgrid groups is constructed. The hierarchical power coordination control model for microgrid groups is expressed as follows:

[0031] ω=ω * -m(PP * )+Δω const +Δω cost

[0032] In the formula: ω represents the output angular frequency; ω * The initial frequency of the control is represented by m; the droop control coefficient is represented by P; and the current active power is represented by P. * Indicates rated active power; Δω const This indicates that the frequency adjustment is based on active power coordination through improved droop control using a consensus algorithm; where:

[0033] ΔΔω const =ω n -const

[0034] ω n The input distributed power source angular frequency is represented by `const`, which is a consistency variable in the consensus protocol. The hierarchical coordination control model of the microgrid group is used to realize the hierarchical coordination control of the microgrid group.

[0035] Furthermore, the calculation of the state of each distributed power source and the increase in power generation cost of the group leader distributed power source based on the coordinated control results using the power generation cost function is specifically as follows:

[0036] The power generation cost function is expressed as follows:

[0037]

[0038] In the formula: α ki βki γ ki For cost parameters; P ki This represents the output power of the i-th distributed power source in the k-th microgrid;

[0039] The output power of each distributed power source is obtained based on the status of the distributed power source and the status of the group leader distributed power source.

[0040] Substituting the output power of each distributed power source into the generation cost function, we obtain the state of each distributed power source and the generation cost increment of the head distributed power source, specifically expressed as follows:

[0041] λ ki =2α ki P ki +β ki

[0042] In the formula, λ ki This represents the increase in generation cost of the i-th distributed power source in the k-th microgrid.

[0043] In the above scheme, by incorporating the increased generation cost as a compensation into the control process, hierarchical coordinated control of islanded AC microgrid groups with coordinated optimization of generation cost and power can be achieved. Attached Figure Description

[0044] Figure 1 This is a schematic diagram of a hierarchical coordinated control method for an isolated AC microgrid group according to an embodiment of the present invention;

[0045] Figure 2 This is a schematic diagram of the physical structure of a microgrid group in one embodiment of the present invention;

[0046] Figure 3 This is a diagram of the overall hierarchical control framework of a microgrid group in one embodiment of the present invention;

[0047] Figure 4 This is a microgrid group communication network topology diagram in one embodiment of the present invention;

[0048] Figure 5 This is a diagram of a hierarchical coordinated control structure for a microgrid group in one embodiment of the present invention;

[0049] Figure 6 This is a topology diagram of a hierarchical control network for an AC microgrid in one embodiment of the present invention;

[0050] Figure 7 This is a diagram of a distributed power supply control structure in one embodiment of the present invention;

[0051] Figure 8 This is a Matlab / Simulink simulation structure diagram of microgrid group consensus protocol control in one embodiment of the present invention;

[0052] Figure 9 This is a Matlab / Simulink simulation structure diagram of the power generation cost constraint consistency protocol in one embodiment of the present invention;

[0053] Figure 10 This is a schematic diagram of the module connection of a hierarchical coordination control system for an islanded AC microgrid group according to one embodiment of the present invention. Detailed Implementation

[0054] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0055] Please see Figure 1 This embodiment provides a hierarchical coordinated control method for an islanded AC microgrid group, including the following steps:

[0056] S1: Obtain the topology parameters of each microgrid and distributed power source in the isolated AC microgrid group, as well as the rated voltage parameters of the microgrid group.

[0057] S2: Based on the topology parameters of microgrids and distributed power sources, microgrid groups are divided into upper-layer networks with microgrids as basic units and lower-layer networks with distributed power sources as basic units.

[0058] S3: Determine the rated voltage parameters of the lower network based on the rated voltage parameters of the microgrid group, and randomly select a distributed power source in the lower network as the group head distributed power source according to the rated voltage parameters of the lower network.

[0059] S4: Obtain the status of each distributed power source and build a lower-level network vertical control model based on the consensus protocol;

[0060] S5: Obtain the status of the distributed power source at the group head and build an upper-layer network vertical control model based on the consensus protocol;

[0061] S6: Coordinated control of the microgrid based on the lower-level network droop control model and the upper-level network droop control model;

[0062] S7: Construct a hierarchical power coordination control model for microgrid groups based on the coordination control results, and realize hierarchical coordination control of microgrid groups based on the hierarchical power coordination control model for microgrid groups.

[0063] In this embodiment, based on the basic topology parameters of the isolated AC microgrid group and distributed power sources, and taking into full account the structure of the microgrid and the connections between microgrids, an upper-layer network with microgrids as the basic unit and a lower-layer network with distributed power sources as the basic unit are established. The droop control models of the lower-layer and upper-layer networks, constructed based on a consensus protocol, can achieve consistent regulation of the system's frequency and voltage during the control process. Based on achieving consistent regulation, a hierarchical power coordination control model for the microgrid group is also constructed, realizing coordinated power control of the hierarchical structure of the microgrid group. This effectively schedules and controls power sharing within the microgrid and power between microgrids, effectively supporting power regulation between different zones during the network recovery phase.

[0064] Furthermore, the specific steps for obtaining the topology parameters of each microgrid and distributed power source in the isolated AC microgrid group, as well as the rated voltage parameters of the microgrid group, are as follows:

[0065] The communication network of the microgrid group is based on the topology parameters of each microgrid and distributed power source in the isolated AC microgrid group, as well as the rated voltage parameters of the microgrid group; the rated voltage parameters of the microgrid group include rated power, rated voltage frequency and amplitude, and unit electricity price.

[0066] Calculate the active and reactive power coefficients for distributed power source droop control based on the rated power, rated voltage, frequency, and amplitude.

[0067] Calculate the generation cost parameters of the distributed power source and microgrid based on the rated power and unit electricity price;

[0068] The active power factor, reactive power factor, and generation cost parameters of the distributed power droop control are all used in the subsequent coordinated control process to improve the voltage frequency and amplitude drop problems existing in traditional droop control.

[0069] An improved droop control method based on consensus protocol is adopted for microgrids and distributed power sources to improve the voltage frequency and amplitude drop problems existing in traditional droop control.

[0070] Furthermore, the step of obtaining the state of each distributed power source and constructing a lower-layer network droop control model based on a consensus protocol specifically involves:

[0071] The status of each distributed power source is obtained based on the communication network between distributed power sources;

[0072] Based on the consensus protocol and the states of each distributed power source, a lower-layer network droop control model is constructed; the lower-layer network droop control model is expressed as follows:

[0073]

[0074] In the formula: τ represents the time constant of the response speed of the lower-layer network; This represents the angular frequency of the i-th distributed power source in the k-th microgrid after control. N represents the voltage after control of the i-th distributed generation in the k-th microgrid; j represents the j-th distributed generation; N k，i Represents the neighborhood set of a distributed power source; Let represent the positive vector of the i-th distributed source in the k-th microgrid; The adjacency matrix element represents the existence of a connection between the i-th and j-th distributed power sources; 0 indicates no connection, 1 indicates a connection. ω represents the angular frequency of the distributed power source before control. k，ch This represents the angular frequency of the distributed generation source at the head of the k-th microgrid group; This indicates whether a connection exists between the i-th distributed power source and the head distributed power source; 0 indicates no connection, 1 indicates a connection. k，ch This represents the voltage of the distributed power source at the head of the k-th microgrid group.

[0075] It should be noted that the lower-layer network droop control model is constructed from a consensus protocol and a traditional droop control process. Combined with the synchronous generator droop control method, traditional droop control can be expressed as:

[0076]

[0077] In the formula: ω * and V * These represent the rated frequency and rated voltage amplitude, respectively; m and n are the active and reactive power coefficients for droop control, respectively; P * and Q * These represent the rated active power and rated reactive power, respectively; ω represents the angular frequency; V represents the system voltage; P represents the active power; and Q represents the reactive power.

[0078] According to the consensus protocol, suppose there are nodes i and j in the matrix:

[0079]

[0080] In the formula x i w represents the state variable. ij This represents the corresponding element in the adjacency matrix of the discrete-time network graph, where u represents the u-th discrete state.

[0081] To facilitate the description and derivation of the microgrid implementation process, a mathematical model of the microgrid is established here. This process is only used as an explanation of the implementation of this technical solution, and the parameters and expressions involved are conventional expressions in this field and should not be interpreted as limiting the scope of protection of this invention.

[0082] Specifically, each independent microgrid is taken as the lower-level network, and the k-th directed graph is denoted as . For n k The k-th microgrid MG from a microsource k Set up a "microgrid agent", i.e., the group's head distributed power source, n k The interconnection topology between -1 ordinary distributed power sources is represented by a directed graph. In this description, each distributed power source is represented as a set of nodes. The connections between distributed power sources are represented as a network link set. The adjacency matrix of the microgrid is and Where if and only if hour, Distributed Power Generation (DG) k,i The neighbor set is composed of Given: Leader adjacency matrix Used to describe "microgrid agent" DG k，ch and n k -1 ordinary distributed power source Interconnection topology between, where if DG k,i Connect to DG k，ch Through fixed links otherwise Among them, for The matrix is ​​a distributed source if and only if the positive vectors At that time, the i-th distributed generation (DG) in the k-th microgrid k,i The angular frequency ω of the "microgrid agent" can be accessed. k,ch and voltage v k,ch τ>0 is the time constant representing the response speed of the lower control layer. Let represent the positive vector of the i-th node in the k-th microgrid.

[0083] Firstly, the droop control of distributed generation in the microgrid is improved using a consensus protocol, namely:

[0084]

[0085]

[0086] In the formula, x i Let i be the state variable of node i. a is the value that the system output approaches after the consensus protocol. ij Let a be the element corresponding to the adjacency matrix in the network graph. If there is a connection between nodes i and j, then a ij =1, otherwise 0.

[0087] Once stable operation is achieved, its output will approach a uniform value.

[0088] It should be further noted that even after improving the droop control of distributed generation in a microgrid using a consensus protocol, issues such as output value drops and slow return to the reference value still exist. The reason for this is that, in addition to achieving parameter synchronization, the consensus protocol also needs to track the parameters; otherwise, stability requirements cannot be met. The synchronization consensus protocol formula is as follows:

[0089]

[0090] In the formula x i Let x be the state variable of node i. ref For the introduced state variable reference value, g i For tracking coefficients.

[0091] Once stable operation is achieved, its output value is:

[0092]

[0093] This yields the consistency protocol after adding synchronization tracking. In this embodiment, const' or x ref As a consistent quantity in a consensus protocol. Based on this, assume... and Each directed graph contains a generating directed tree, and is represented by a positive vector. and Perform a detailed balancing. (Result) and It is positive definite, and the Laplace matrix L is positive definite. k and respectively with A k and This refers to the topological mathematical relationship between upper and lower layers of networks in a microgrid cluster.

[0094] For multiple distributed generation sources in a single microgrid, the aforementioned synchronization and consistency protocol is incorporated into the control process, and the difference Δx between ordinary distributed generation source i and ordinary distributed generation source j is derived respectively. i,j And the difference Δx between the "microgrid agent" and the i-th ordinary distributed power source. i,ch ,have:

[0095] Δx i,j =x k,j -x k,i

[0096] Δx i,ch =x k,ch -x k,i

[0097] Δx i,j and Δxi,ch Substituting this into the synchronization-introduced consensus protocol, multiplying the state variables by a time constant yields the following control method:

[0098]

[0099] Thus, the droop control model of the lower-level network can be obtained.

[0100] This embodiment introduces a tracking step, which can effectively solve the problem of slow numerical regression speed in traditional droop control.

[0101] Furthermore, the step of obtaining the state of the distributed power source at the group head and constructing an upper-layer network droop control model based on a consensus protocol specifically involves:

[0102] The status of the group leader distributed power source, including voltage frequency and amplitude, is obtained based on the communication network between distributed power sources.

[0103] Based on the consensus protocol and the state of the distributed power source at the group head, an upper-layer network droop control model is constructed; the upper-layer network droop control model is expressed as follows:

[0104]

[0105] In the formula: T represents the time constant of the upper-layer network response speed; Represents the angular frequency of the distributed generation at the head of the k-th microgrid after control. represents the voltage after the distributed generation at the group head in the k-th microgrid is controlled; l represents the l-th microgrid; This represents the neighborhood of the k-th microgrid; This represents the positive vector of the k-th microgrid; This indicates whether a connection exists between the k-th microgrid and the l-th distributed power source; 0 indicates no connection and 1 indicates a connection exists. This indicates whether a connection exists between the k-th microgrid and the reference microgrid; 0 indicates no connection, and 1 indicates a connection. rated Indicates the reference angular frequency; v rated This represents the reference voltage.

[0106] In this embodiment, the design principle of the upper-layer network droop control model is the same as that of the lower-layer network droop control model described above, and will not be elaborated further here.

[0107] In this embodiment, a consistency protocol is added to the traditional droop control, which can ensure the consistent adjustment of the system's frequency and voltage during the control process and avoid the voltage frequency or amplitude drop problems caused by traditional droop control.

[0108] Furthermore, a hierarchical power coordination control model for the microgrid group is constructed based on the coordination control results, and hierarchical coordination control of the microgrid group is realized based on the hierarchical power coordination control model, specifically as follows:

[0109] Based on the coordinated control results, the state of each distributed power source and the increase in the power generation cost of the head distributed power source are calculated using the power generation cost function.

[0110] Based on the principle of minimum power generation cost with constant increments, an optimal active power reduction model is constructed; the optimal active power reduction model is expressed as:

[0111] Δω cost =k ed λ ki (P ki )

[0112] In the formula: ω cost This represents the angular frequency of the distributed power source after cost optimization; k ed λ represents the positive scalar coefficient. ki (P ki ) represents the incremental value function of power generation cost; Δω cost Indicates the rate of slight increase in power generation costs;

[0113] Based on the increase in power generation costs and the optimal active power reduction model, a hierarchical power coordination control model for microgrid groups is constructed. The hierarchical power coordination control model for microgrid groups is expressed as follows:

[0114] ω=ω * -m(PP * )+Δω const +Δω cost

[0115] In the formula: ω represents the output angular frequency; ω * The initial frequency of the control is represented by m; the droop control coefficient is represented by P; and the current active power is represented by P. * Indicates rated active power; Δω const This indicates that the frequency adjustment is based on active power coordination through improved droop control using a consensus algorithm; where:

[0116] Δω const =ω n -const

[0117] ω n The input distributed power source angular frequency is represented by `const`, which is a consistency variable in the consensus protocol. The hierarchical coordination control model of the microgrid group is used to realize the hierarchical coordination control of the microgrid group.

[0118] Furthermore, the calculation of the state of each distributed power source and the increase in power generation cost of the group leader distributed power source based on the coordinated control results using the power generation cost function is specifically as follows:

[0119] The power generation cost function is expressed as follows:

[0120]

[0121] In the formula: α ki β ki γ ki For cost parameters; P ki This represents the output power of the i-th distributed power source in the k-th microgrid;

[0122] The output power of each distributed power source is obtained based on the status of the distributed power source and the status of the group leader distributed power source.

[0123] Substituting the output power of each distributed power source into the generation cost function, we obtain the state of each distributed power source and the generation cost increment of the head distributed power source, specifically expressed as follows:

[0124] λ ki =2α ki P ki +β ki

[0125] In the formula, λ ki This represents the increase in generation cost of the i-th distributed power source in the k-th microgrid.

[0126] In this embodiment, by incorporating the increased generation cost as a compensation into the control process, hierarchical coordinated control of islanded AC microgrid groups with coordinated optimization of generation cost and power can be achieved.

[0127] It should be noted that, in this embodiment, the microgrid group hierarchical power coordination control model is based on the principle of minimizing total generation cost in the economic dispatch problem. It controls generation cost by designing a decreasing equation for active power. The total generation cost of the microgrid group system can be minimized through constraints, achieving cost constraints. Specifically, the i-th distributed generation source (DG) in the k-th microgrid... ki The power generation cost function is denoted as GC. ki (P ki Therefore, the k-th microgrid MG k The economic dispatch problem, also known as the problem of minimizing the overall power generation cost, can be expressed as:

[0128]

[0129]

[0130] Where P Load For microgrids MG k The total load power. Lagrange multiplication can be used to solve optimization problems related to power generation costs. The Lagrange function L... ag The construction is as follows:

[0131]

[0132] In the formula, λ is the Lagrange multiplier. Based on the optimality condition, we can derive:

[0133]

[0134] in It's DG ki The increment in power generation cost can be denoted as λ. ki (P ki Based on this formula, we can conclude that:

[0135]

[0136] This is the principle of constant increment in the economic dispatch problem that minimizes the total generation cost. Therefore, based on this, we can design the optimal active power reduction equation, which is:

[0137] Δω cost =k ed λ ki (P ki )

[0138] When the control system is in steady state, the angular frequencies of all distributed power sources are ω cost If all values ​​remain consistent, then the value also satisfies the principle of equal increment. Therefore, the total power generation cost of the microgrid group system can be minimized through constraints, thus achieving cost constraints.

[0139] This embodiment proposes a hierarchical coordinated control method for isolated AC microgrid groups, which realizes coordinated control of power in the hierarchical structure of microgrid groups. It can effectively schedule and control power sharing within the microgrid and power between microgrids, and effectively support power regulation between different zones during the network recovery phase.

[0140] To further realize the hierarchical coordinated control method for isolated AC microgrid groups, this embodiment specifically designs a physical structure for the microgrid group. Please refer to [link to relevant documentation]. Figure 2 In this system, DG stands for Distributed Generation, and Load refers to the load corresponding to each Distributed Generation. Each microgrid group has a group leader Distributed Generation that acts as a "microgrid agent" to communicate with other "microgrid agents" to exchange data and facilitate economic power allocation.

[0141] After establishing the physical structure of the microgrid cluster, a hierarchical overall control framework for the microgrid cluster was designed. The hierarchical control framework for the microgrid cluster is as follows: Figure 3 As shown, its control framework can be roughly divided into three layers: the first layer is the distributed power generation layer, which directly implements droop control for each distributed power generation; the second layer is the microgrid layer, which achieves coordination and consistency within the microgrid through distributed control; and the third layer is the central control layer of the microgrid group, which achieves overall consistency control of the microgrid through the control of the microgrid agents.

[0142] Next, please see Figure 4 Microgrids exist as sub-units within a microgrid cluster, requiring the design of control strategies for distributed power sources. This involves ensuring the stable operation of individual microgrids and then coordinating the output of each microgrid to optimize the overall cluster operation. Each distributed power source's distributed secondary controller in a microgrid is an intelligent agent with multiple functions, including sensing, computing, and communication. Therefore, a microgrid can be viewed as a distributed multi-agent system. Nodes within a microgrid exchange information with neighboring nodes via a distributed sparse network, forming a networked multi-agent system. The topological relationships between these agents can be described using algebraic graphs (directed or undirected), which can be used to analyze the coordinated control relationships among the agents.

[0143] The communication network of a microgrid cluster also needs to be layered, just like its physical structure. First, the bottom-layer network of the microgrid cluster is established. The microgrid itself, as the lower-layer network, comprises M directed graphs, i.e. arrive For n k The k-th microgrid MG from a microsource k Set up a "microgrid agent", n k The interconnection topology between -1 ordinary distributed power sources is represented by a directed graph. Description, node set Network Links Adjacency matrix and , where if and only if hour, Distributed Power Generation (DG) k,i The neighbor set is composed of Given: Leader adjacency matrix Used to describe "microgrid agent" DG k，ch and n k -1 ordinary distributed power source Interconnection topology between, where if DG k,i Connect to DG k，ch Through fixed links otherwise

[0144] After establishing the underlying communication network within the microgrid, we establish an upper-level communication network between microgrids. It can be a set of nodes with "microgrid agent" The lower-level generation reference. Network link set. Adjacency matrix DG k,ch The neighbor set is To adjust each DG k,ch The frequency / voltage introduces a leader adjacency matrix. If this matrix is ​​available to DG k,ch ,but otherwise

[0145] Assumption and Each directed graph contains a generating directed tree, and is represented by a positive vector. and Perform a detailed balancing. Then, and It is positive definite, and the Laplace matrix L is positive definite. k and respectively with A K and This refers to the topological mathematical relationship between upper and lower layers of networks in a microgrid cluster.

[0146] Furthermore, the design of the communication network and the control method for the microgrid group were completed.

[0147] Microgrid systems are often characterized by large numbers and high uncertainty; therefore, distributed control methods are chosen to control the individual units within the microgrid system. Distributed control of microgrid systems relies on distributed consensus protocols to drive consistency of certain variables among the system units or to restore voltage and frequency to their average estimates. Hierarchical control of a microgrid group can employ a simple first-order discrete consensus algorithm, which can be derived from a first-order continuous consensus algorithm. In a microgrid system, the state variables of node i (physical quantities such as voltage and frequency of the microgrid system) are represented by x. i This indicates that nodes in the system only communicate with their neighboring nodes. Therefore, the system achieves uniform convergence if and only if the state variables of all nodes are identical. The first-order continuous-time consensus algorithm is as follows:

[0148]

[0149] In the formula, x i Represents the state variable, u i a represents the control variable. ijThis represents the corresponding element in the adjacency matrix of the network graph, as described above, N. i Let a represent the other nodes connected to node i in the matrix. If there is a connection between nodes i and j, then a ij =1, otherwise 0.

[0150] Based on the properties of the Laplace matrix, this expression can be presented in matrix form:

[0151]

[0152] In the formula, X represents the matrix composed of the relevant physical quantities of each node, and L is the Laplace matrix, which is related to the network topology. Therefore, the expression for the discrete consensus algorithm can be written using the continuous-time consensus algorithm:

[0153]

[0154] i = 1, 2, ..., n

[0155] In the formula w ij Let represent the corresponding element in the adjacency matrix of the discrete-time network graph, where u represents the u-th discrete state. Similarly, its matrix form is expressed as: X(u+1)=WX(u), where W∈R. n×n Let be the state transition matrix of the system.

[0156] To overcome the shortcomings of simple droop control, this embodiment uses a consensus protocol to adjust various parameters. The consensus protocol enables consistency in frequency and voltage within the system, but it also requires reference values ​​to ensure the parameters reach their expected values. Based on the aforementioned discrete consensus algorithm, the state variables in the algorithm are converted into voltage frequency and amplitude. In the two-layer network, the droop control model of the lower layer network can be designed as follows:

[0157]

[0158] After designing the physical structure, communication network, and control methods, the physical layer, network layer, and control layer are connected through, for example... Figure 5The method shown is used to couple and complete the design of a hierarchical coordinated control structure for a microgrid group. In the microgrid group system, controlled sources can be designed as ideal distributed power sources. Droop control is used to control reactive and active power output to ensure stable voltage and frequency output, forming microgrid modules. The combination of microgrid modules can form a microgrid group. A communication network is formed through "microgrid proxies" within the microgrid modules to achieve power control between microgrid groups. A power economic allocation network parallel to the power sharing network is also designed through "microgrid proxies" that serve as the source of microgrid parameters, achieving cost constraints. Each distributed power source maintains consistency with the grid using droop control, and adjacent distributed power sources form a communication network. The upper-level communication network achieves power sharing among distributed power sources through a consensus algorithm.

[0159] Please see Figure 6 This is a topology diagram of a hierarchical control network for an AC microgrid. This embodiment considers a two-level power management strategy for AC microgrid clusters, where all distributed power sources are divided into "microgrid agents" and ordinary distributed power sources, which constitute the upper and lower control layers, respectively. The upper-layer control scheme ensures economical power distribution among microgrid clusters by transferring power flow between any two "microgrid agents," while the lower-layer control scheme ensures power sharing within each microgrid cluster by controlling ordinary distributed power sources to track the data of the "microgrid agents." Simultaneously, primary control adjusts the voltage frequency and amplitude based on the power output of the "microgrid agents" and droop control feedback to address power mismatch in the upper-layer network.

[0160] At this point, the microgrid has formed a microgrid cluster. A communication network is established through "microgrid agents" within the microgrid modules, enabling coordinated power control among the microgrid clusters. Based on this, this embodiment can implement a power-economical distribution network parallel to the power-sharing network. Cost constraints are achieved through the design of the "microgrid agent," which serves as the source of microgrid parameters. In the simulation, an ideal distributed power source can be designed as a single-phase controlled source. The distributed power source control structure is as follows: Figure 7 As shown, each distributed power source maintains consistency with the grid using droop control, and a communication network is formed between adjacent distributed power sources; the upper-level communication network realizes power sharing among distributed power sources through a consensus algorithm.

[0161] The primary goal of a microgrid cluster system is to ensure stable power quality. Therefore, the most fundamental aspect of voltage stability control among microgrids is through power coordination. The improved droop control based on a consensus protocol used within the microgrid effectively achieves rapid frequency and amplitude adjustment in primary control, enabling parameters to return to a normal range. Therefore, this embodiment considers each "microgrid agent" as the basic unit for feeding back microgrid parameters in the upper-level network of the microgrid cluster, using a consensus protocol to ensure parameter coordination among the microgrids within the cluster.

[0162] When implementing power coordination control for a microgrid cluster, only one distributed power source needs to be selected in each microgrid as the node for data exchange between the clusters. In this embodiment, the selected "microgrid agent" exists in different topologies and has different parameters in different microgrids to achieve design universality. The design of the controller for the voltage frequency and amplitude consistency protocol between microgrids in the microgrid cluster, i.e., the upper-layer network droop control model, is as follows:

[0163]

[0164] in The positive vector representing the k-th microgrid is defined if and only if the adjacency matrix element... At that time, "microgrid agent" DG k,ch The reference angular frequency ω can be accessed. rated and voltage v rated T>0, where T is the time constant of the upper control layer. This controller uses a microgrid group consensus protocol. Its Matlab / Simulink simulation model is as follows: Figure 8 As shown in the figure, fp_q represents the q-th distributed power source in the p-th microgrid (a unique "microgrid agent" randomly selected in this microgrid), a represents the control coefficient, and the positive vector in the figure is the above equation. This represents the integral term, where fref_value represents the reference value of the voltage frequency, and f_delta represents the compensation amount of the reference value to the system.

[0165] In a microgrid cluster, each distributed power source needs to consider load demand and generation costs during microgrid operation, achieving economical power allocation within the microgrid system through cost constraints. To simulate the relationship between distributed power generation and load demand in a microgrid cluster, this embodiment models the generation cost constraint based on the power coordination control in the original secondary control. The mathematical model of the generation cost constraint is specifically explained as follows:

[0166] The i-th distributed generation (DG) in the k-th microgrid ki The power generation cost function is denoted as GC. ki (P kiTherefore, the k-th microgrid MG k The economic dispatch problem, also known as the problem of minimizing the overall power generation cost, can be expressed as:

[0167]

[0168]

[0169] Where P Load For microgrids MG k The total load power. Lagrange multiplication can be used to solve optimization problems related to power generation costs. The Lagrange function L... ag The construction is as follows:

[0170]

[0171] In the formula, λ is the Lagrange multiplier. Based on the optimality condition, we can derive:

[0172]

[0173] in It's DG ki The increment in power generation cost can be denoted as λ. ki (P ki Based on this formula, we can conclude that:

[0174]

[0175] This is the principle of constant increment in the economic dispatch problem that minimizes the total generation cost. Therefore, the optimal active power reduction equation can be designed as follows:

[0176] Δω cost =k ed λ ki (P ki )

[0177] Where ω cost To achieve the cost-optimized distributed power source angular frequency, k ed It is a positive scalar coefficient. Its active power decrease will be introduced into droop control to achieve control optimization. In steady state, the angular frequency ω of all distributed power sources... cost If all values ​​remain consistent, then the value also satisfies the principle of equal increment. Therefore, the total power generation cost of the microgrid group system can be minimized through constraints, thus achieving cost constraints.

[0178] In this embodiment, the generation cost function GC of the i-th distributed power source in the k-th microgrid is... ki (P ki Its power generation is described by a quadratic function, expressed as:

[0179]

[0180] Where α ki β ki γ ki For cost parameters.

[0181] Based on the power generation cost function, the incremental value λ of the power generation cost of the microgrid group can be obtained. ki Its expression is:

[0182] λ ki =2α ki P ki +β ki

[0183] Based on the established mathematical model of power generation cost constraints, the incremental cost rate can be added as a compensation to the secondary control module to realize the design of a hierarchical coordinated control method for a complete islanded AC microgrid group. The control module formula is as follows:

[0184] ω=ω * -m(PP * )+Δω const +Δω cost

[0185] In the formula ω * Let Δω be the initial frequency of the system. cost Δω represents the incremental cost rate of active power reduction feedback to primary control based on cost optimization. const To improve droop control based on a consensus algorithm, the adjustment frequency is coordinated by active power. The generation cost-constrained consensus protocol is simulated using Matlab / Simulink. Figure 9 As shown in the figure, wrefp_q represents the q-th distributed generation of the p-th microgrid (a unique "microgrid agent" randomly selected in this microgrid), wn is the system frequency reference value, and wsys_star is the system initial frequency ω. * wref_cost is the incremental cost rate Δω cost lamk is the incremental value of the generation cost of the k-th microgrid. k ked is a positive scalar coefficient, cw1 is a frequency control coefficient, and cp1 is a power generation cost increment control coefficient.

[0186] This embodiment first constructs a bottom-layer communication network for the microgrid cluster based on the internal structure of the microgrid. Considering the interconnections between microgrids, it establishes an upper-layer communication network between microgrids, using a directed tree to describe the topological relationships between the upper and lower layers. A consensus protocol is employed to adjust system parameters, achieving consistent frequency and voltage regulation. A secondary power management strategy for the AC microgrid cluster is designed to realize economic power allocation and power sharing among microgrids. Power generation cost constraints are modeled based on the power coordination control in the original secondary control. The control method described in this embodiment can provide a hierarchical control method during post-disaster islanding interconnection and power mutual assistance, effectively scheduling power sharing within the microgrid and power scheduling control between microgrids, effectively supporting power regulation between different zones during network recovery.

[0187] This embodiment is not limited to microgrid structures, but aims to extend to the scheduling and control between various small distribution networks, providing a reference for guiding power regulation between network zones after a disaster.

[0188] Please see Figure 10 This embodiment proposes a hierarchical coordinated control system for an isolated AC microgrid group, including a data acquisition module, a network partitioning module, a microgrid proxy module, a lower-level network droop control module, an upper-level network droop control module, a coordination control module, and a power coordination control module for the hierarchical structure of the power grid group; wherein:

[0189] The data acquisition module is used to acquire the topology parameters of each microgrid and distributed power source in the isolated AC microgrid group, as well as the rated voltage parameters of the microgrid group.

[0190] The network partitioning module is used to divide the microgrid group into an upper-layer network with microgrids as the basic unit and a lower-layer network with distributed power sources as the basic unit, based on the topology parameters of the microgrid and distributed power sources.

[0191] The microgrid proxy module is used to determine the rated voltage parameters of the lower network based on the rated voltage parameters of the microgrid group, and randomly select a distributed power source in the lower network as the group head distributed power source according to the rated voltage parameters of the lower network.

[0192] The lower-layer network droop control module is used to obtain the status of each distributed power source and construct a lower-layer network droop control model based on a consensus protocol.

[0193] The upper-layer network droop control module is used to obtain the status of the distributed power source at the group head and construct the upper-layer network droop control model based on the consensus protocol.

[0194] The coordination control module is used to coordinate and control the microgrid based on the lower-level network droop control model and the upper-level network droop control model.

[0195] The power coordination control module for the power grid group hierarchical structure is used to construct a power coordination control model for the microgrid group hierarchical structure based on the coordination control results, and to realize hierarchical coordination control of the microgrid group based on the power coordination control model for the microgrid group hierarchical structure.

[0196] Furthermore, the lower-layer network droop control module is used to obtain the status of each distributed power source and construct a lower-layer network droop control model based on a consensus protocol, specifically as follows:

[0197] The status of each distributed power source is obtained based on the communication network between distributed power sources;

[0198] Based on the consensus protocol and the states of each distributed power source, a lower-layer network droop control model is constructed; the lower-layer network droop control model is expressed as follows:

[0199]

[0200] In the formula: τ represents the time constant of the response speed of the lower-layer network; This represents the angular frequency of the i-th distributed power source in the k-th microgrid after control. N represents the voltage after control of the i-th distributed generation in the k-th microgrid; j represents the j-th distributed generation; N k，i Represents the neighborhood set of a distributed power source; Let represent the positive vector of the i-th distributed source in the k-th microgrid; The adjacency matrix element represents the existence of a connection between the i-th and j-th distributed power sources; 0 indicates no connection, 1 indicates a connection. ω represents the angular frequency of the distributed power source before control. k，ch This represents the angular frequency of the distributed generation source at the head of the k-th microgrid group; This indicates whether a connection exists between the i-th distributed power source and the head distributed power source; 0 indicates no connection, 1 indicates a connection. k，ch This represents the voltage of the distributed power source at the head of the k-th microgrid group.

[0201] Furthermore, the upper-layer network droop control module is used to obtain the state of the distributed power source at the group head and construct an upper-layer network droop control model based on a consensus protocol, specifically as follows:

[0202] The status of the group leader distributed power source is obtained based on the communication network between distributed power sources.

[0203] Based on the consensus protocol and the state of the distributed power source at the group head, an upper-layer network droop control model is constructed; the upper-layer network droop control model is expressed as follows:

[0204]

[0205] In the formula: T represents the time constant of the upper-layer network response speed; Represents the angular frequency of the distributed generation at the head of the k-th microgrid after control. represents the voltage after the distributed generation at the group head in the k-th microgrid is controlled; l represents the l-th microgrid; This represents the neighborhood of the k-th microgrid; This represents the positive vector of the k-th microgrid; This indicates whether a connection exists between the k-th microgrid and the l-th distributed power source; 0 indicates no connection and 1 indicates a connection exists. This indicates whether a connection exists between the k-th microgrid and the reference microgrid; 0 indicates no connection, and 1 indicates a connection. rated Indicates the reference angular frequency; v rated This represents the reference voltage.

[0206] Furthermore, the power coordination control module for the microgrid group hierarchical structure is used to construct a power coordination control model for the microgrid group hierarchical structure based on the coordination control results, and to realize hierarchical coordination control of the microgrid group based on the power coordination control model for the microgrid group, specifically as follows:

[0207] Based on the coordinated control results, the state of each distributed power source and the increase in the power generation cost of the head distributed power source are calculated using the power generation cost function.

[0208] Based on the principle of minimum power generation cost with constant increments, an optimal active power reduction model is constructed; the optimal active power reduction model is expressed as:

[0209] Δω cost =k ed λ ki (P ki )

[0210] In the formula: ω cost This represents the angular frequency of the distributed power source after cost optimization; k ed λ represents the positive scalar coefficient. ki (P ki ) represents the incremental value function of power generation cost; Δω cost Indicates the rate of slight increase in power generation costs;

[0211] Based on the increase in power generation costs and the optimal active power reduction model, a hierarchical power coordination control model for microgrid groups is constructed. The hierarchical power coordination control model for microgrid groups is expressed as follows:

[0212] ω=ω * -m(PP * )+Δω const +Δω cost

[0213] In the formula: ω represents the output angular frequency; ω * The initial frequency of the control is represented by m; the droop control coefficient is represented by P; and the current active power is represented by P. * Indicates rated active power; Δω const This indicates that the frequency adjustment is based on active power coordination through improved droop control using a consensus algorithm; where:

[0214] Δω const =ω n -const

[0215] ω n The input distributed power source angular frequency is represented by `const`, which is a consistency variable in the consensus protocol. The hierarchical coordination control model of the microgrid group is used to realize the hierarchical coordination control of the microgrid group.

[0216] Furthermore, the calculation of the state of each distributed power source and the increase in power generation cost of the group leader distributed power source based on the coordinated control results using the power generation cost function is specifically as follows:

[0217] The power generation cost function is expressed as follows:

[0218]

[0219] In the formula: α ki β ki γ ki For cost parameters; P ki This represents the output power of the i-th distributed power source in the k-th microgrid;

[0220] The output power of each distributed power source is obtained based on the status of the distributed power source and the status of the group leader distributed power source.

[0221] Substituting the output power of each distributed power source into the generation cost function, we obtain the state of each distributed power source and the generation cost increment of the head distributed power source, specifically expressed as follows:

[0222] λ ki =2α ki P ki +β ki

[0223] In the formula, λ ki This represents the increase in generation cost of the i-th distributed power source in the k-th microgrid.

[0224] This embodiment provides a hierarchical coordinated control system for an isolated AC microgrid group, which implements a hierarchical coordinated control method for an isolated AC microgrid group. Based on the basic topology parameters of the isolated AC microgrid group and distributed generation, it fully considers the structure of the microgrid and the connections between microgrids, establishing an upper-layer network with microgrids as the basic unit and a lower-layer network with distributed generation as the basic unit. Based on a consensus protocol, a droop control model for the lower-layer network and an upper-layer network are constructed to achieve consistent regulation of the system's frequency and voltage during the control process. On the basis of achieving consistent regulation, a hierarchical power coordination control model for the microgrid group is also constructed, realizing coordinated power control of the hierarchical structure of the microgrid group. This effectively enables power sharing within the microgrid and power scheduling control between microgrids, effectively supporting power regulation between different zones during the network recovery phase.

[0225] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A hierarchical coordinated control method for an islanded AC microgrid group, characterized in that, Includes the following steps: Obtain the topology parameters of each microgrid and distributed power source in the isolated AC microgrid group, as well as the rated voltage parameters of the microgrid group; Based on the topology parameters of microgrids and distributed generation, microgrid groups are divided into upper-layer networks with microgrids as the basic unit and lower-layer networks with distributed generation as the basic unit. The rated voltage parameters of the lower network are determined based on the rated voltage parameters of the microgrid group, and a distributed power source is randomly selected from the lower network as the group head distributed power source according to the rated voltage parameters of the lower network. The status of each distributed power source is obtained based on the communication network between distributed power sources, and a lower-level network droop control model is constructed based on a consensus protocol. The lower-level network droop control model is expressed as follows: In the formula: The time constant representing the response speed of the lower-layer network; Indicates the first k The first microgrid i angular frequency after control of a distributed power source; Indicates the first k The first microgrid i Voltage after control of a distributed power source; Indicates the first One distributed power source; Represents the neighborhood set of a distributed power source; Indicates the first k The first microgrid i A positive vector of distributed power sources; Represents the adjacency matrix element, representing the first element. The distributed power source to the first The value is 0 if the connection of the distributed power source does not exist, and 1 if it does exist. Indicates the angular frequency before distributed power source control; Indicates the first k The angular frequency of the first distributed power source in a microgrid cluster; Indicates the first If a connection exists between a distributed power source and the group's head distributed power source, the value is 0; if it does not exist, the value is 1. Indicates the first k The voltage of the first distributed power source in a microgrid cluster; The state of the group leader distributed power source is obtained based on the communication network among distributed power sources, and an upper-layer network droop control model is constructed based on a consensus protocol. The upper-layer network droop control model is expressed as follows: In the formula: T The time constant representing the response speed of the upper-layer network; Indicates the first k angular frequency after the control of distributed power sources at the head of a microgrid; Indicates the first k The voltage after the distributed power source control of the group head in a microgrid; Indicates the first Microgrids; Indicates the first The neighborhood set of a microgrid; Indicates the first A positive vector of a microgrid; Indicates the first microgrid to the first The value is 0 if the connection of the distributed power source does not exist, and 1 if it does exist. Indicates the first The value is 0 if the connection between the microgrid and the reference microgrid does not exist, and 1 if it does exist. Indicates the reference angular frequency; Indicates the reference voltage; Coordinated control of microgrids is achieved based on lower-level network droop control models and upper-level network droop control models. Based on the coordinated control results, a hierarchical power coordinated control model for microgrid groups is constructed, and hierarchical coordinated control of microgrid groups is realized based on the hierarchical power coordinated control model for microgrid groups.

2. The hierarchical coordinated control method for an islanded AC microgrid group according to claim 1, characterized in that, Based on the coordinated control results, a hierarchical power coordinated control model for microgrid groups is constructed, and hierarchical coordinated control of the microgrid groups is implemented based on this model. Specifically: Based on the coordinated control results, the state of each distributed power source and the increase in the power generation cost of the head distributed power source are calculated using the power generation cost function. Based on the principle of minimum power generation cost with constant increments, an optimal active power reduction model is constructed; the optimal active power reduction model is expressed as: In the formula: This represents the angular frequency of the distributed power source after cost optimization. Indicates a positive scalar coefficient; A function representing the incremental value of power generation costs; Indicates the rate of slight increase in power generation costs; Based on the increase in power generation costs and the optimal active power reduction model, a hierarchical power coordination control model for microgrid groups is constructed. The hierarchical power coordination control model for microgrid groups is expressed as follows: In the formula: Indicates the output angular frequency; Indicates the initial frequency of control; Indicates the droop control coefficient; Indicates the current active power; Indicates the rated active power; This indicates that the frequency adjustment is based on active power coordination through improved droop control using a consensus algorithm; where: This represents the angular frequency of the input distributed power source, where const is a consistency variable in the consensus protocol. A hierarchical coordinated control model for microgrid groups is implemented based on a power coordination control model for the hierarchical structure of microgrid groups.

3. The hierarchical coordinated control method for an islanded AC microgrid group according to claim 2, characterized in that, Based on the coordinated control results, the state of each distributed power source and the increase in power generation cost of the head distributed power source are calculated using a power generation cost function. Specifically: The power generation cost function is expressed as follows: In the formula: , , For cost parameters; Indicates the first The first in the microgrid The output power of a distributed power source; The output power of each distributed power source is obtained based on the status of the distributed power source and the status of the group leader distributed power source. Substituting the output power of each distributed power source into the generation cost function, we obtain the state of each distributed power source and the generation cost increment of the head distributed power source, specifically expressed as follows: In the formula, Indicates the first The first in the microgrid The increase in generation cost of a distributed power source.

4. A hierarchical coordinated control system for an isolated AC microgrid group, characterized in that, It includes a data acquisition module, a network partitioning module, a microgrid proxy module, a lower-level network droop control module, an upper-level network droop control module, a coordination control module, and a power coordination control module for the hierarchical structure of the power grid group; among which: The data acquisition module is used to acquire the topology parameters of each microgrid and distributed power source in the isolated AC microgrid group, as well as the rated voltage parameters of the microgrid group. The network partitioning module is used to divide the microgrid group into an upper-layer network with microgrids as the basic unit and a lower-layer network with distributed power sources as the basic unit, based on the topology parameters of the microgrid and distributed power sources. The microgrid proxy module is used to determine the rated voltage parameters of the lower network based on the rated voltage parameters of the microgrid group, and randomly select a distributed power source in the lower network as the group head distributed power source according to the rated voltage parameters of the lower network. The lower-layer network droop control module is used to obtain the status of each distributed power source according to the communication network between distributed power sources and construct a lower-layer network droop control model based on a consensus protocol. The lower-layer network droop control model is expressed as follows: In the formula: The time constant representing the response speed of the lower-layer network; Indicates the first k The first microgrid i angular frequency after control of a distributed power source; Indicates the first k The first microgrid i Voltage after control of a distributed power source; Indicates the first One distributed power source; Represents the neighborhood set of a distributed power source; Indicates the first k The first microgrid i A positive vector of distributed power sources; Represents the adjacency matrix element, representing the first element. The distributed power source to the first The value is 0 if the connection of the distributed power source does not exist, and 1 if it does exist. Indicates the angular frequency before distributed power source control; Indicates the first k The angular frequency of the first distributed power source in a microgrid cluster; Indicates the first If a connection exists between a distributed power source and the group's head distributed power source, the value is 0; if it does not exist, the value is 1. Indicates the first k The voltage of the first distributed power source in a microgrid cluster; The upper-layer network droop control module is used to obtain the state of the group head distributed power source according to the communication network between distributed power sources and construct an upper-layer network droop control model based on a consensus protocol. The upper-layer network droop control model is represented as follows: In the formula: T The time constant representing the response speed of the upper-layer network; Indicates the first k angular frequency after the control of distributed power sources at the head of a microgrid; Indicates the first k The voltage after the distributed power source control of the group head in a microgrid; Indicates the first Microgrids; Indicates the first The neighborhood set of a microgrid; Indicates the first A positive vector of a microgrid; Indicates the first microgrid to the first The value is 0 if the connection of the distributed power source does not exist, and 1 if it does exist. Indicates the first The value is 0 if the connection between the microgrid and the reference microgrid does not exist, and 1 if it does exist. Indicates the reference angular frequency; Indicates the reference voltage; The coordination control module is used to coordinate and control the microgrid based on the lower-level network droop control model and the upper-level network droop control model. The power coordination control module for the power grid group hierarchical structure is used to construct a power coordination control model for the microgrid group hierarchical structure based on the coordination control results, and to realize hierarchical coordination control of the microgrid group based on the power coordination control model for the microgrid group hierarchical structure.

5. The hierarchical coordinated control system for an isolated AC microgrid group according to claim 4, characterized in that, The power coordination control module for the microgrid group's hierarchical structure is used to construct a power coordination control model for the microgrid group's hierarchical structure based on the coordination control results, and to realize hierarchical coordination control of the microgrid group based on the microgrid group's hierarchical structure power coordination control model, specifically: Based on the coordinated control results, the state of each distributed power source and the increase in the power generation cost of the head distributed power source are calculated using the power generation cost function. Based on the principle of minimum power generation cost with constant increments, an optimal active power reduction model is constructed; the optimal active power reduction model is expressed as: In the formula: This represents the angular frequency of the distributed power source after cost optimization. Indicates a positive scalar coefficient; A function representing the incremental value of power generation costs; Indicates the rate of slight increase in power generation costs; Based on the increase in power generation costs and the optimal active power reduction model, a hierarchical power coordination control model for microgrid groups is constructed. The hierarchical power coordination control model for microgrid groups is expressed as follows: In the formula: Indicates the output angular frequency; Indicates the initial frequency of control; Indicates the droop control coefficient; Indicates the current active power; Indicates the rated active power; This indicates that the frequency adjustment is based on active power coordination through improved droop control using a consensus algorithm; where: This represents the angular frequency of the input distributed power source, where const is a consistency variable in the consensus protocol. A hierarchical coordinated control model for microgrid groups is implemented based on a power coordination control model for the hierarchical structure of microgrid groups.

6. The hierarchical coordinated control system for an islanded AC microgrid group according to claim 5, characterized in that, Based on the coordinated control results, the state of each distributed power source and the increase in power generation cost of the head distributed power source are calculated using a power generation cost function. Specifically: The power generation cost function is expressed as follows: In the formula: , , For cost parameters; Indicates the first The first in the microgrid The output power of a distributed power source; The output power of each distributed power source is obtained based on the status of the distributed power source and the status of the group leader distributed power source. Substituting the output power of each distributed power source into the generation cost function, we obtain the state of each distributed power source and the generation cost increment of the head distributed power source, specifically expressed as follows: In the formula, Indicates the first The first in the microgrid The increase in generation cost of a distributed power source.

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